Recently, there has been provided a digital camera which is capable of recording of high-speed moving images such as HD (high-definition) moving images. In response to a demand in still image capture, a 12-megapixel image sensor is used. On the other hand, the number of pixels of an HD moving image outputted is horizontal 1920 pixels by vertical 1080 pixels, and therefore, its total number of pixels is 2.1 megapixels. Accordingly, in order to realize a digital camera capable of capturing a high-definition still image and an HD moving image with a same image sensor, it is necessary to limit the number of pixel signals outputted from the image sensor in moving image capture.
A known method to limit the number of pixel signals outputted from the image sensor is cut-out output in which a part of a screen is cut out and then outputted. For example, in the cut-out output, an image sensor capable of outputting a 12-megapixel still image outputs a 2.1-megapixel moving image in such a way that a central part of the screen which is approximately one-quarter of the entire screen is cut out and outputted. However, this method is disadvantageous in that the angle of view in moving image capture is narrower than that in still image capture.
As other method to limit the number of pixel signals outputted from the image sensor, there has been known: decimation output in which pixel signals are outputted after some of them are decimated; and pixel mixture output in which a plurality of pixel signals of a same color are mixed with one another and then outputted (see Patent Literatures 1, 2, and 3). For example, by performing decimation or pixel mixture, a signal for one pixel is outputted based on signals for vertical 2 pixels by horizontal 2 pixels, and thereby an output data rate is reduced to ¼.
Prior Art Document
Patent Literature
    Patent Literature 1: Japanese Unexamined Patent Publication No. 2005-244995    Patent Literature 2: Japanese Unexamined Patent Publication No. 2009-159186    Patent Literature 3: Japanese Unexamined Patent Publication No. 2009-147489